Improvement in countersinks



UNITED STATES PATENT OFFICE.

H. S. SHEPARDSON, OF SHELBURNE FALLS, MASSACHUSETTS, ASSIGNOR TO HIMSELF AND F. R. PRATT AND W. I-I. MAYNARD, ALL OF SAME PLACE.

IMPROVEMENT IN COUNTERSINKS.

Specification forming part of Letters Patent No. 4 |894, dated March 8, 1864.

To @ZZ whom, it may concern.-

Be it known that I, H. S. SHEPARDsoN, of Shelburne Falls, in the county of Franklin and State of Massachusetts, have invented certain new and useful Improvements in Oountersinks to be Used with Boring-Tools; and I do hereby declare the following to be a full, clear, and exact description of the same,

reference being had to the accompanying drawings, making a part of this specication, in Which- Figure l represents a boring-tool with the countersink attached thereto. Fig. 2 repre sents, on an enlarged scale, the better to show its form and construction, the countersink detached.

Countersinks have been made to be attached to boring-tools, but from their imperfect construction and operation have failed to go into practical use. My invention makes the countersinks easily detachable and adjustable, and very simple and efficient. Moreover, its cutting-lip works concentrically with' the bit, and its throat follows the line of the throat or spiral of the bit, and thus causes it to work freely and truly with the boring-tool.

To enable others skilled in the art to make and use my invention, I will proceed to describe the same with reference to the draw- 1n gs.

A represents theboring-bit, which may be of any of the usual Well-known kinds, and B and used therewith. The countersink partially surrounds the shank of the bit1 and is adj usted and fastened thereto by a set-screw,

a, the point of which rests againt the spiral groove of the bit. The cutting-lip c of the countersink Works concentrically with the bit, and the clearance or throat e matches the clearance or spiral of the bit, so that the action of the countersink conforms to that of the bit, and makes a true concentric countersink for the head of the screw. The portion f of the countersink acts as a gage to define the depth-to which the countersink can Work. By making the countersink toonly partially surround the shank of the bit it may be applied or removed from the shank laterally, instead of slipping it over the end ofthe bit.

Having thus fully described my invention, what I claim therein as new, and desire. to secure by Letters Patent, in a countersink tol be used with a boring-tool, is-

The making of the countersink to onlypartially surround the shank of the bit, and the cutting-lip to work concentrically with the bit,'and the throat of the countersink to conform to the clearance of the bit, all as herein described and represented. Y H. S. SHEPARDSON.

Witnesses:

H. A. MERRITT, y JOHN V. GEIEBEL. 

